It has proved necessary to follow the speeds of means of transport, especially vehicles used in road traffic. A particular need has been evident as regards avoidance of traffic jams and road planning, whereby vehicle-specific data collection performed in real time will allow statistic analysing of the traffic as well as a comparison of performance.
Good methods exist for following spot speeds, for example, the police use radars in their traffic control. Besides these, it is possible to use measuring loops reacting to vehicles driving over them. However, neither radars nor measuring loops are able to individualise the vehicle, and it is not possible to measure e.g. reliable average speeds.
For example, in the Helsinki region picture identification methods have been used in connection with traffic data collection. At a road section a camera is placed to take pictures of passing vehicles. At another place along the road another camera is situated to take corresponding pictures. An analysing system, which may be close to real time at best, identifies the licence plates of the vehicles in the pictures. When both cameras have taken a picture of the same licence plate, it is possible reliably to determine the average speed of the vehicle in the picture. In Holland they have also connected a speeding ticket printout device to the analysing system to print out payment orders to the persons in possession of the speeding motorcars.
When real-time traffic data is desired from the area of a large road network, the picture identification method described above has such drawbacks as big investments, because it is expensive to build and maintain the measuring points. In addition, data transmission connections cost money, and the calculation capacity needed for picture identification is not either free. The method is also exposed to weather conditions, which reduces usability especially in countries where much rain, snow or fog will occur.
It has long been known to use a network of mobile stations to localise the subscriber. Using a network of mobile stations also for collection of traffic information is very well known. In the following, reference is made to two publications, U.S. Pat. No. 5,933,100 and WO 01/23835, as the state of the art.
The U.S. Pat. No. 5,933,100 shows how measurement data of a GPS system is transmitted by a mobile station to a data system, which calculates the average speed on each road section in the road network.
In PCT application publication WO 01/23835 special software is located on the terminal equipment to follow the changing of cells in the network of mobile stations and to report on the changes to the system. In one embodiment, the system computes the location of the mobile station and the speed of the mobile station based on the location of the base transceiver station and on the distance between the terminal equipment and the base transceiver station.
In another embodiment (pages 61–63 of the PCT publication) it is proposed that the location of the mobile station can be collected from the base transceiver stations in flight. The information to be collected may concern e.g. periodic beacon transmissions from the terminal equipment to the network. It is also mentioned in the application publication that the location of the mobile station may travel through the service switching point of the mobile station system, whereby the above-mentioned periodic beacon transmissions may be collected from the traffic in the service switching point.
In view of the equipment belonging to the users of the mobile station system, the solution presented in application publication WO 01/23835 does not seem operable, but it contains fundamental problems. Firstly, the terminal equipment is required to transmit extra messages to the network, which will cause unnecessary loading of the air interface in areas with much traffic. In addition, the unnecessary traffic will add to the power consumption of the terminal equipment. Secondly, the presented solution requires changes to the terminal equipment, e.g. mounting of an additional application, which means that the solution cannot be implemented with the existing mobile stations and that the same implementation will not necessarily function on the terminal equipment of two different manufacturers. Thirdly, collecting messages of the network will not necessarily succeed, if some messages travel in a protected form.
Thus, the known art gives no solution model for a method and system, wherein traffic data is collected by using a mobile station system without changes to be made in ordinary mobile stations or without necessary actions by the user. In addition, one of the most difficult problems of the state of the art relates to protection of the individual. The user's privacy is jeopardised, if his movements are being tracked, even allowing that such tracking is for the public good. If such a system is used for collecting traffic data, wherein the users are identifiable, then consent by the users is required even in the smallest possible case. It would be difficult if a user would not give his consent when such generally applicable methods are worked out, which concern all users of the network.